1. Field of the Invention
This invention relates to a printing apparatus for performing a prepress process to record an image on a blank printing plate held on a plate cylinder, and then performing a printing process to transfer ink supplied to the printing plate, through a blanket cylinder, to printing paper held on an impression cylinder.
2. Description of the Related Art 
A known printing apparatus for performing a prepress process to record an image on a blank printing plate held on a plate cylinder, and then performing a printing process to transfer ink supplied to the printing plate, through a blanket cylinder, to printing paper held on an impression cylinder is described in Japanese Unexamined Patent Publication No. 11-77965 (1999), for example.
The apparatus described in the above publication includes a forward end clamp mechanism arranged on the plate cylinder and having a clamp and a clamp seat. The clamp and clamp seat hold therebetween the forward end of the printing plate mounted peripherally of the plate cylinder. This apparatus further includes a squeeze roller movable between a squeeze position adjacent the surface of the plate cylinder for squeezing, against the periphery of the plate cylinder, the printing plate having the forward end thereof held between the clamp and clamp seat of the forward end  clamp mechanism, and a standby position spaced away from the surface of the plate cylinder. Thus, the above apparatus can hold the printing plate peripherally of the plate cylinder without slackening the printing plate.
However, since an ink feeder is disposed in the apparatus described in Japanese Unexamined Patent Publication No. 11-77965 (1999), the ink flowing out of the ink feeder could adhere to the squeeze roller as ink mist, for example. In this case, when the blank printing plate not yet having an image recorded thereon is squeezed by the squeeze roller stained with ink mist or the like, the stains may be transferred to the printing plate. This poses a problem of hampering subsequent image recording operations.